Method and apparatus for controlling transmission of content data

ABSTRACT

Provided are a method and apparatus for controlling transmission of content data. In the method, a communication channel is initially established to transmit the content data, the content data is transmitted through the established communication channel, verification is performed a plurality of times to determine whether the content data is transmitted within an acceptable transmission range, and whether to continue the transmission of the content data is determined according to the verification result. Accordingly, when a client moves to a location outside a predetermined acceptable transmission range in a wireless environment, a server stops transmission of the content data. In addition, content data can be continuously transmitted regardless of interference caused by a temporary obstacle between a server and a client.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application claims the benefit of Korean Patent Application No.10-2007-0034420, filed on Apr. 6, 2007, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Methods and apparatuses consistent with the present invention relate tocontrolling transmission of content data, and more particularly, tocontrolling transmission of content data, in which a communicationchannel is initially established to transmit the content data, thecontent data is then transmitted through the established communicationchannel, verification is then performed a plurality of times todetermine whether the content data is transmitted within an acceptabletransmission range, and whether to continue the transmission of thecontent data is then determined according to the verification result.

2. Description of the Related Art

In a wired communication environment, data communication can be reliablyachieved between devices since, once an initial session is establishedbetween a server and a client, the location of a receiving end and adata arrival time do not change while data is being transmitted. On theother hand, in a wireless communication environment, some problems mayoccur such as data transmission collision, data loss, etc. This isbecause several factors interrupt reliable communication in the wirelesscommunication environment. Examples of such factors include use of amulti-path scheme, fading, interference, etc.

In the wireless communication environment, a server may determine anacceptable transmission range (or local range) in addition to anaccessible range in which communication is available. Since a pluralityof anonymous devices may receive radio waves in the accessible range inthe wireless communication environment, the server must properly limitthe acceptable transmission range.

In this case, a localization process is performed. The localizationprocess is defined as a process of verifying whether a client is locatedwithin a limited acceptable transmission range. In general, thelocalization process is carried out by using a method of restricting around trip time (RTT) of a packet transmitted between a server and aclient so that the RTT is below a predetermined value.

FIG. 1 is a view for explaining a conventional method of transmittingcontent data between a server and a client.

Referring to FIG. 1, data has been conventionally transmitted between aserver 110 and a client 120 in the following procedure. The client 120requests the server 110 for content data (operation 130). In order todecide validity of the client 120, the server 110 performs an operationfor mutual authentication and session key exchange (operation 140). Forexample, authentication and key exchange (AKE) is performed when using adigital transmission content protection over Internet protocol(DTCP/IP). The aforementioned localization operation is performed whileexchanging a challenge key or an exchange key. When the AKE issuccessful, the server 110 transmits the content data requested by theclient 120 (operations 150 to 170).

However, conventionally, the localization operation is performed onlyonce when the AKE is carried out while an initial session isestablished, and thereafter the server 10 continuously transmits thecontent data to the client 120. Thus, the server 110 may continuouslytransmit the content data even when the client 120 is located at a latertime in a position where a localization condition is not satisfied. Inaddition, localization may fail when interference temporarily occurs inthe process of localization due to a certain obstacle, and thus theserver 110 may stop the transmission of the content data.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for controllingtransmission of content data, in which a communication channel isinitially established to transmit the content data, the content data istransmitted through the established communication channel, verificationis performed a plurality of times to determine whether the content datais transmitted within an acceptable transmission range, and whether tocontinue the transmission of the content data is determined according tothe verification result.

According to an aspect of the present invention, there is provided amethod of controlling transmission of content data, the methodincluding: initially establishing a communication channel through whichthe content data is transmitted; transmitting the content data throughthe communication channel; verifying a plurality of times whether thecontent data is transmitted within an acceptable transmission range; anddetermining whether to transmit the content data according to theverification result.

The operation of determining whether to transmit the content data may beperformed according to a ratio of how many times the content data istransmitted within the acceptable transmission range to how many timesverification is attempted in the verifying a plurality of times whetherthe content data is transmitted within the acceptable transmissionrange.

In the operation of determining whether to transmit the content data,the transmission of the content data may be stopped when the ratio isless than a threshold level.

In the operation of verifying, verification may be periodicallyperformed according to a specific time interval, or according to anamount of the content data to be transmitted.

In the operation of verifying, an RTT (round trip time) of a packet maybe measured while transmitting the content data so as to determinewhether the content data is transmitted within an acceptabletransmission range.

In the operation of initial establishing a communication channel, an AKE(authentication and key exchange) operation may be performed.

In the operation of determining whether to transmit the content data, aflag may be set to determine whether the content data can be stored.

According to another aspect of the present invention, there is providedan apparatus for controlling transmission of content data, the apparatusincluding: a session establisher initially establishing a communicationchannel through which the content data is transmitted; a datatransmitter transmitting the content data through the communicationchannel established by the session establisher; a localization unitverifying a plurality of times whether the content data transmitted fromthe data transmitter is transmitted within an acceptable transmissionrange; and a data transmission controller determining whether totransmit the content data according to the verification resultdetermined by the localization unit.

The data transmission controller may determine whether to transmit thecontent data according to a ratio of how many times the content data istransmitted within the acceptable transmission range to how many timesverification is attempted by the localization unit.

The data transmission controller may stop the transmission of thecontent data when the ratio is less than a threshold level.

The localization unit may periodically perform verification according toa specific time interval, or according to an amount of the content datato be transmitted.

The localization unit may measure an RTT (round trip time) of a packetwhile transmitting the content data so as to determine whether thecontent data is transmitted within the acceptable transmission range.

The session establisher may perform an AKE (authentication and keyexchange) operation. The data transmitter may transmit the content dataregardless of whether the content is transmitted within the acceptabletransmission range after the AKE operation is performed.

The data transmission controller may set a flag to determine whether thecontent data can be stored.

According to another aspect of the present invention, there is provideda computer-readable medium having embodied thereon a computer programfor executing a method of controlling transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention will become moreapparent by describing in detail exemplary embodiments thereof withreference to the attached drawings in which:

FIG. 1 is a view for explaining a conventional method of transmittingcontent data between a server and a client;

FIG. 2 is a flowchart of a method of controlling transmission of contentdata according to an embodiment of the present invention;

FIG. 3 is a view for explaining a method of transmitting content databetween a server and a client according to an embodiment of the presentinvention;

FIG. 4 is a flowchart of a method of controlling transmission of contentdata according to another embodiment of the present invention;

FIG. 5 is a view for explaining a method of transmitting content databetween a server and a client according to another embodiment of thepresent invention; and

FIG. 6 is a block diagram of an apparatus for controlling transmissionof content data according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Exemplary embodiments of the present invention will now be described indetail with reference to the accompanying drawings.

FIG. 2 is a flowchart of a method of controlling transmission of contentdata according to an embodiment of the present invention.

Referring to FIG. 2, the method includes: initially establishing acommunication channel through which the content data is transmitted(operation 210); transmitting the content data through the establishedcommunication channel (operation 220); performing localization aplurality of times to verity whether the content data is transmittedwithin an acceptable transmission range (operation 230); and determiningwhether to transmit the content data according to the verificationresult (operation 240).

In operation 210, a communication state is initiated before the contentdata is transmitted. That is, in order to establish the communicationchannel, a session is connected between a server and a client accordingto a session initialization protocol. In an embodiment the client may bean external device.

In operation 220, the content data is transmitted through thecommunication channel. The content data may be transmitted prior to orat the same time as the localization which is performed to verifywhether the client is located within a limited acceptable transmissionrange (or local area). When the content data is transmitted prior to thelocalization, a sort of open document (e.g., advertisement broadcasting,information message, etc.), which is not restricted to a dedicatedclient but is open to third parties, may be transmitted.

In operation 230, such a localization operation is performed a pluralityof times to verify whether the client is located within the limitedacceptable transmission range. The localization operation is performedwhile the content data is transmitted. The localization operationperformed a plurality of times may be regularly performed according to aspecific time interval or may be periodically performed according to theamount of content data to be transmitted.

In operation 240, it is determined whether to continue the transmissionof the content data according to the localization result. If thelocalization is successful, the transmission of the content data iscontinued. Otherwise, the client is regarded as being located outsidethe acceptable transmission range, thereby stopping the transmission ofthe content data. Afterwards, when the client requests re-transmissionof the content data, the server may be subject to the aforementionedsession initialization and localization operations so as to retransmitthe content data.

The data transmission process between the server and the client will nowbe described further with reference to FIG. 3.

FIG. 3 is a view for explaining a method of transmitting content databetween a server and a client, e.g., an external device, according to anembodiment of the present invention.

Data transmission between a server 310 and a client 320 is achievedaccording to the method of controlling transmission of content data ofthe present invention.

Referring to FIG. 3, when the client 320 requests the server 310 totransmit content data (operation 330), the server 310 and the client 320exchange mutual authentication and session keys (e.g., authenticationand key exchange (AKE) in digital transmission content protection overInternet protocol (DTCP/IP)) (operation 340). When AKE is successful(operation 340), the server 310 transmits the content data to the client320. At the same time, the server 310 performs a localization operationto verify whether the client 320 is located within an acceptabletransmission range (operation 350). When the localization operation issuccessful, the transmission of the content data is continued (operation360). Operations 350 and 360 are repeated in this manner until thetransmission of the content data is ended.

FIG. 4 is a flowchart of a method of controlling transmission of contentdata according to another embodiment of the present invention.

Referring to FIG. 4, as described above, AKE is performed whentransmission of content data is requested (operation 410).

When the AKE is successful, the content data is transmitted (operation420). In this process 420, since localization is not yet performed, acertain amount (or a certain time period) of content data is transmittedregardless of whether the client, e.g., an external device, is locatedwithin a currently acceptable transmission range.

Thereafter, localization is performed by measuring a round trip time(RTT) of a packet transmitted by the server. The measured RTT iscompared with a predetermined threshold level. If the RTT is greaterthen the threshold level, that is, a delay time is long, it can bedetermined that the client is located outside the acceptabletransmission range (i.e., localization has failed or is unsatisfied).

In order to obtain a highly reliable RTT, the RTT measurement isperformed N times rather than one time (operation 430). If localizationis successful K times when RTT measurement is performed N times, aprobability P can be obtained from a ratio therebetween. If theprobability P is greater than a threshold level, it is determined thatlocalization is successful (operation 440). The transmission of thecontent data is continued until a final localization result is obtained,that is, until the RTT measurement is carried out N times.

According to the probability P indicating how many times localizationhas been successfully performed out of a total of N attempts, thetransmission of the content data is either continued (operation 450) orstopped (operation 460). The decision on whether content transmissionwill be continued to transmit next content data may be periodicallyperformed according to a predetermined time interval or according to theamount of content data transmitted. Furthermore, even after it isdecided that the content data be continuously transmitted, a flag may beset to determine whether the content data being transmitted can bereproduced and stored.

FIG. 5 is a view for explaining a method of transmitting content databetween a server and a client according to another embodiment of thepresent invention.

Data transmission between a server 510 and a client 520, e.g., anexternal device, is achieved using the method of controllingtransmission of content data according to an embodiment of the presentinvention as shown in FIG. 4.

Referring to FIG. 5, when the client 520 requests the server 510 totransmit content data (operation 530), the server 510 and the client 520perform an AKE operation (operation 540).

When the AKE operation is successful (operation 540), the server 510performs a localization operation (operations 550 a to 570 b). Asdescribed above, the localization operation is repeated by using an RTTfrom a first operation 550 b to an N-th operation 570 b. A probability Pis calculated using the total number of times K successful localizationsare performed and the total number of times N the localizationoperations are performed. Whether the client 520 satisfies thelocalization condition is determined according to the probability P. Thetransmission of the content data is continued until the localization isperformed N times (operations 550 a, 560 a, and 570 a). A highlyreliable RTT can be obtained by performing verification N times. Inaddition thereto, the content data can be continuously transmitted evenwhen temporary interference occurs (e.g., due to an obstacle) betweenthe server 510 and the client 520.

Upon completing localization N times, the transmission of the contentdata is either continued or stopped according to the calculatedprobability P (operation 580). The localization or the transmission ofthe content data is periodically performed according to a time sequenceor the amount of content data to be transmitted. Accordingly, since thelocalization is periodically performed a plurality of times, thelocation of a client can be accurately detected even when the clientmoves to another location after a first localization is performed.

Meanwhile, whether a final localization is satisfied may be determinedby computing a mean value M of RTT values measured N times and thencomparing the mean value with a threshold level.

FIG. 6 is a block diagram of an apparatus for controlling transmissionof content data according to an embodiment of the present invention.

Referring to FIG. 6, an apparatus 600 for controlling transmission ofcontent data includes a session establisher 610 which initiallyestablishes a communication channel through which the content data istransmitted, a data transmitter 620 which transmits the content datathrough the communication channel, a localization unit 630 whichverifies a plurality of times whether the content data is transmittedwithin an acceptable transmission range, and a data transmissioncontroller 640 which determines whether to continue the transmission ofthe content data according to the verification result.

The session establisher 610 initiates a communication state before thecontent data is transmitted. In other words, the session establisher 610establishes an initialization session. The data transmitter 620transmits the content data through the channel established by thesession establisher 610.

The localization unit 630 performs localization to verify whether theclient, e.g., an external device, is located within an acceptabletransmission range. This verification operation is performed a pluralityof times. The localization operation is performed while the content datais transmitted. The localization operation performed a plurality oftimes may be regularly performed according to a specific time intervalor may be periodically performed according to the amount of content datato be transmitted.

If the localization unit 630 determines that localization is successful,the data transmission controller 640 continuously transmits the contentdata. Otherwise, the client is regarded as being located outside theacceptable transmission range, thereby stopping the transmission of thecontent data.

Although it has been described that content data is mainly transmittedfrom a server to a client in the aforementioned embodiments of thepresent invention, the present invention also applies when the contentdata is transmitted from the client to the server.

According to a method and apparatus for controlling transmission ofcontent data of the present invention, when a client moves to a locationoutside a predetermined acceptable transmission range in a wirelessenvironment, a server stops transmission of the content data. Forexample, if localization is successful when a client of a user accessesa server of a neighbor while the user is visiting the neighbor,transmission of content data may be continued even after the user comesback to his/her home. This can be prevented by the present invention.

In addition, the probability of localization may be calculated so thatcontent data can be continuously transmitted regardless of interferencecaused by a temporary obstacle between a server and a client.

The invention can also be embodied as computer readable codes on acomputer readable recording medium. The computer readable recordingmedium is any data storage device that can store data which can bethereafter read by a computer system. Examples of the computer readablerecording medium include read-only memory (ROM), random-access memory(RAM), CD-ROMs, magnetic tapes, floppy disks and optical data storagedevices. The computer readable recording medium can also be distributedover network coupled computer systems so that the computer readable codeis stored and executed in a distributed fashion.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the invention as defined by the appended claims. The exemplaryembodiments should be considered in descriptive sense only and not forpurposes of limitation. Therefore, the scope of the invention is definednot by the detailed description of the invention but by the appendedclaims, and all differences within the scope will be construed as beingincluded in the present invention.

What is claimed is:
 1. A method of controlling transmission of contentdata, the method comprising: establishing a communication channel withan external device; sequentially transmitting a first, second, third, .. . , Nth pieces of the content data through the communication channelto the external device; verifying, subsequent to transmitting eachfirst, second, . . . , (N−1)th piece of the content data and prior totransmitting the next one of the second, third, . . . , Nth pieces ofthe content data, whether the first, second, . . . , (N−1)th pieces ofthe content data are transmitted to the external device within anacceptable transmission range to generate a verification result; anddetermining whether to transmit the next one of the second, third, . . ., Nth pieces of the content data according to the verification result,wherein the verifying comprises measuring a round trip time (RTT) of apacket to determine whether the first, second, . . . , (N−1)th pieces ofthe content data are transmitted to the external device within theacceptable transmission range and wherein, in the verifying,verification is periodically performed according to an amount Of thecontent data to be transmitted.
 2. The method of claim 1, wherein, thedetermining of whether to transmit the next one of the second, third, .. . , Nth pieces of the content data is performed according to a ratioof a number of times the first, second, . . . , (N−1)th pieces of thecontent data are transmitted to the external device within theacceptable transmission range to a number of times venfication isattempted.
 3. The method of claim 2, wherein, m the determining whetherto transmit the next one of the second, third, . . . , Nth pieces of thecontent data, the transmission of the content data is stopped if theratio is less than a threshold level.
 4. The method of claim 1, wherein,m the initial establishing of a communication channel, an authenticationand key exchange (AKE) operation is performed.
 5. The method of claim 4,wherein, m the establishing of a communication channel, after the AKEoperation is performed, the first piece of the content data istransmitted regardless of whether the first piece of the content istransmitted to the external device within the acceptable transmissionrange.
 6. The method of claim 5, wherein, m the determining of whetherto transmit the next one of the second, third, . . . , Nth pieces of thecontent data, a flag is set to determine whether the content data can bestored.
 7. An apparatus for controlling transmission of content data,the apparatus comprising: a hardware processor comprising: a sessionestablisher which establishes a communication channel with an externaldevice; a data transmitter which sequentially transmits a first, second,third, . . . , Nth pieces of the content data through the communicationchannel to the external device; a localization unit which verifies,subsequent to transmitting each first, second, . . . , (N−1)th piece ofthe content data and prior to transmitting the next one of the second,third, . . . , Nth pieces of the content data, whether the first,second, . . . , (N−1)th pieces of the content data transmitted from thedata transmitter are transmitted to the external device within anacceptable transmission range to generate a verification result; and adata transmission controller which determines whether to transmit thenext one of the second, third, . . . , Nth pieces of the content dataaccording to the verification result determined by the localizationunit, wherein the localization unit measures a round trip time (RTT) ofa packet to determine whether the first, second, . . . , (N−1)th piecesof the content data are transmitted to the external device within theacceptable transmission range, and the localization unit periodicallyperforms verification according to an amount of the content data to betransmitted.
 8. The apparatus of claim 7, wherein the data transmissioncontroller determines whether to transmit the next one of the second,third, . . . , Nth pieces of the content data according to a ratio of anumber of times the first, second, . . . , (N−1)th pieces of the contentdata are transmitted to the external device within the acceptabletransmission range to a number of times verification is attempted by thelocalization unit.
 9. The apparatus of claim 8, wherein the datatransmission controller stops the transmission of the content data ifthe ratio is less than a threshold level.
 10. The apparatus of claim 7,wherein the session establisher performs an authentication and keyexchange (AKE) operation.
 11. The apparatus of claim 10, wherein thedata transmitter transmits the first piece of the content dataregardless of whether the first piece of the content is transmitted tothe external device within the acceptable transmission range after theAKE operation is performed.
 12. The apparatus of claim 11, wherein thedata transmission controller sets a flag to determine whether thecontent data can be stored.
 13. A non-transitory computer-readablemedium having embodied thereon a computer program which when executed bya computer causes the computer to execute the method of: establishing acommunication channel with an external device; sequentially transmittinga first, second, third, . . . , Nth pieces of the content data throughthe communication channel to the external device; verifying, subsequentto transmitting each first, second, . . . , (N−1)th piece of the contentdata and prior to transmitting the next one of the second, third, . . ., Nth pieces of the content data, whether the first, second, . . . ,(N−1)th pieces of the content data are transmitted to the externaldevice within an acceptable transmission range to generate averification result; and determining whether to transmit the next one ofthe second, third, . . . , Nth pieces of the content data according tothe verification result, wherein the verifying comprises measuring around trip time (RTT) of a packet to determine whether the first,second, . . . , (N−1)th pieces of the content data are transmitted tothe external device within the acceptable transmission range, wherein,in the verifying, verification is periodically performed according to anamount of the content data to be transmitted.
 14. The method of claim 1,further comprising receiving, from the external device, a request totransfer the content data, prior to the establishing the communicationchannel with the external device, wherein the verifying comprises:verifying, during the transmitting of the content data, the plurality oftimes whether the content data is transmitted to the external devicewithin the acceptable transmission range while the requested contentdata is being transmitted.